Traditionally, most magnetic disk drives have operated in a Contact Start-Stop (CSS) mode in which heads come to rest on the disk surface when the drive is turned off. During start-up, the heads contact and slide over a Laser Zone Textured (LZT) portion of the disk surface until the disks are spinning sufficiently fast for the slider to fly above the disk surface. The LZT provides a roughened surface that prevents adhesion (or reduces stiction) of the head to the smooth disk surface and removes contaminant and disk lubricant particles from the Air Bearing Surface or ABS of the slider (which includes the Giant MagnetoResistive or GMR head). The ABS typically includes the trailing center pad and other minimum slider-to-disk clearance pads. Particle buildup on the ABS can create potential performance degradation of the GMR head, causing the head to roll or otherwise have an improper height above the disk surface. An improper flying height can lead to unacceptable read/write error rates. The landing zone does not contain data and is used solely for slider starting and stopping cycles.
Load/unload disk drives have become an attractive alternative to CSS disk drives. Compared to CSS disk drives, load/unload drives provide benefits including increased areal density for higher capacity, improved shock resistance for greater disk durability and longevity, and reduced power consumption for cost savings. A conventional load/unload design is shown in FIG. 1. The disk drive 100 includes a magnetic disk 104, a rotary actuator arm 108 mounting a flexible suspension arm 112 and a slider 116. A tab 112 extends from the flexible suspension arm 112 for engaging a ramp 120 when the rotary arm 108 is moved to a rest or parked position, such as at power-down. The ramp 120 is an inclined cam-like surface, commonly positioned at the disk outer diameter. The tab 112 causes the arm 108 to ride upwards in response to the incline of the ramp until the tab 112 is parked at a detent 124 located at the parked position. The head is returned to the disk 104 only after a sufficient rotation rate has been reached on the next start-up cycle to permit the slider to fly above the disk surface. In this disk drive design unlike CSS disk drives, head-to-disk contact (and any other head-to-disk interaction) is drastically reduced, thereby virtually eliminating disk and/or head damage.
However, intermittent head-to-disk contact can cause disk lubricant and other contaminant particles to buildup on the head, causing impaired drive performance. In the load/unload design, there is no regular or controlled contact between the ABS surface of the slider and the disk to remove the particulates accumulated on the slider/head as may occur in a CSS design. To address this problem, one load/unload disk drive design placed a cleaning brush in an off-disk position. After the tab has contacted the ramp and as the tab is moving up the ramp incline, the brush contacts and cleans the slider/head. The brush thus effects head cleaning during each power-down and power-up cycle. Although this design did provide some particulate removal, cleaning occurred infrequently during power-down and power-up cycles. The cleaning was also of limited effectiveness because the cleaning action was in a cross-track direction and loading pressure of the head on the brush was low.